Rudolf Steiner discusses the nature of warmth, its relationship to the four states of matter, to light, to color, and to the sub-earthly and super-earthly realms. He strives to extend modern ideas of physics through the understandings achieved by spiritual science. With extensive notes and diagrams, this work comprises essential reference material for teachers of the natural sciences, as well as interested parents and others.
Fourteen lectures Stuttgart 1-14 March 1920